Background

Published estimates of depression in the perinatal period (pregnancy and up to twelve months postpartum), vary widely. A recent meta-analysis reported point prevalence estimates of depression between 8.5% and 11% among pregnant women and 6.5% to 12.9% among postpartum women [1].

According to the most recent Census estimates, Latinos continue to be the largest minority group in the United States, accounting for 15% of the total population [2]. Latinas have the highest birthrates of all racial/ethnic groups in the U.S. [3]. Despite the growing importance of Latinas in the U.S., there is limited information about the levels of perinatal depression in this growing population group [1]. In particular, within the constellation of known risk factors, such as social support and a history of depression, little is known about how acculturation affects the level of depression and depressive symptoms among Latinas in the U.S. during the perinatal period.

Acculturation, or, the experience of an immigrant’s adaptation to a host country has also been described as “Americanization”, whereby an immigrant becomes assimilated into American society [4]. Simply put, low acculturation suggests that an individual has not adopted the U.S. lifestyle, while high acculturation denotes the opposite [5, 6]. Earlier research found that U.S.-born, more acculturated Latinos of Mexican-origin experienced less mental health problems when compared to less acculturated, Mexican-born Latinos [4]. This research was based on a prevailing psychiatric paradigm, linking immigration-related stress with psychopathology [4]. Such thinking led researchers to believe that acculturation to American society would be a key factor in improving immigrants’ health, including mental health [7–9]. Large scale population-based research from such studies as the Epidemiologic Catchment Area (ECA) Study and the Hispanic Health and Nutrition Examination Survey (HHANES) has challenged this hypothesis [4]. For example, among Mexican-origin adults who took part in the HHANES, higher acculturation was identified as a risk factor for depressive symptoms [10]. The ECA Study conducted in Los Angeles found Mexican-born Latinos experienced a significantly lower level of lifetime prevalence of major depression when compared to U.S.-born Latinos [4]. An analysis of data collected from the National Comorbidity Study (NCS) found that more acculturated Mexican-origin Latinos reported a higher prevalence of psychiatric disorders than less acculturated Mexican-origin Latinos [11]. Such findings have led researchers to conclude a protective effect among Mexican-origin Latino immigrants, translating into favorable mental health outcomes when compared to native-born Latinos.

The few studies of acculturation and perinatal depressive symptoms have had inconsistent results [12]. A recent study of new mothers found Latinas born outside the U.S. had a lower prevalence of depressive symptoms than their U.S.-born counterparts [13], however, two other studies found no differences in depressive symptoms when comparing U.S.-born to foreign-born Latinas [14, 15]. Beck (2006) in her review of acculturation and its implications for perinatal research attributed the inconsistency to different methods of measurement. For example, Heilemann et al. (2004), who used birthplace and language preference as acculturation indicators, reported no differences in depressive symptoms during the postpartum period between U.S.- and Mexican-born Latinas. In this same study, the indicator of age at immigration was related to depressive symptoms, in that women who had spent their childhood in Mexico and immigrated to the U.S. at an older age had lower levels of depressive symptoms compared to women who had immigrated at a younger age and had spent their childhood in the U.S. [12, 16]. Thus, the evidence is conflicting as to whether or not high acculturation is a risk factor for perinatal depressive symptoms among Latinas.

Acculturation has been measured as self-identification (e.g. Mexican-American or Anglo), the number of years an immigrant has spent in the U.S., and the fluency a Latino has with the English language [10, 17]. Several acculturation scales have been developed, e.g., the Acculturation Rating Scale for Mexican- Americans (ARSMA) [5]. Such scales typically include items related to language usage and self-identification, but may also include media usage and ethnic behaviors related to food and music [12]. However, in a review of immigration and mental health among Mexican-origin adults in the U.S., Escobar et al. (2000) found language use and place of birth to be the key factors in determining acculturation level. Recent methodological critiques have recommended the use of individual indicators, such as place of birth, age of immigration to the U.S., years residing in the U.S., and primary language use, in lieu of acculturation scales, because they are commonly included in studies conducted by the U.S. Census Bureau and other major health surveys [18].

This purpose of this study is to assess the prevalence of moderate to high and high (elevated), depressive symptoms among pregnant and postpartum U.S.- and Mexican-born Latinas attending a public health clinic in San Antonio, Texas using birth country and language of interview as acculturation indicators. Its second aim is to describe the relation of elevated depressive symptoms to potential risk factors, including birth country, age, marital and pregnancy status.

Methods

Study Design

The study is a secondary data analysis of data collected as part of the Perinatal Depression Project for Healthy Start, conducted by the San Antonio Metropolitan Health District (SAMHD). Healthy Start is a population-based intervention designed to address infant mortality and poor birth outcomes in San Antonio, Texas. The purpose of this project was to provide information to support program development of an infrastructure within SAMHD for the provision of mental health services to pregnant and postpartum women. As such, the instrument created included a limited number of questions thought to be most relevant to program planners. The study was conducted in eight Family Planning Clinics and six Prenatal Clinics of the SAMHD between May and August of 2003. All SAMHD public health clinics that provide family planning and prenatal care services participated in the study.

Sample and Data Collection

Recruitment and interviewing was conducted by three trained, bilingual interviewers. They recruited women who came to one of the family planning or prenatal clinics for the following reasons: (1) a prenatal visit, (2) a postpartum visit, (3) a well-child or immunization visit for their infant, or 4) to have a pregnancy test conducted. As the patient arrived for her visit and signed-in for her appointment, she was approached by an interviewer and asked to answer a few questions pertaining to how she had been feeling during the previous week. If she agreed to participate, the interviewer described the study and obtained written consent for her participation in the questioning and to obtain selected information from her medical chart. Once consent forms were signed, the actual interview was conducted in a private setting at the clinic in the language of the respondent’s choice, either English or Spanish. The average number of patients served on a monthly basis in the fourteen clinics was 900 women, clearly more than could be interviewed by three interviewers.

The sample is a convenience sample of 455 pregnant and postpartum women (up to one year postpartum), that attended any one of the SAMHD’s family planning or prenatal care clinics and self-identified as Latina. This analysis excludes 14 women born in Central and South American countries so as to compare Latinas born in the U.S. and Mexico. Although U.S.-born Latinas were not asked about their ethnic origin, the majority of Latinos in Texas are of Mexican-origin, accounting for 76% of the total Latino population [19]. In addition, two cases were dropped due to extensive missing data, leaving 439 cases for analysis: 318 Mexican-born and 121 U.S.-born women.

Interviewers did not collect the number of women approached who declined to participate in the original study. Based on a comparison of unduplicated clients served by each clinic during the months of April, June, July and August of 2003 (records for the month of May could not be located), the sample captured 13% of family planning clients and 24% of prenatal clients.

Data were collected using two instruments. The Demographic Intake Form captured basic demographic information on the woman and her pregnancy: date of the interview, clinic, name of interviewer, age and year of birth, marital status, race/ethnicity, country of birth (respondent), number of children, pregnancy status (pregnant/postpartum), and timing of last birth or number of months pregnant. Items used to assess acculturation were birth country and language of interview. The second instrument, used to screen for depressive symptoms, was the Center for Epidemiologic Studies Depression Scale (CES-D), a self-report inventory of 20 questions about depressive symptoms.

The interviewers were provided with a written protocol so that participants who indicated significant depressive symptoms could be referred for treatment. The protocol used scores suggested by Barnes and Prosen [20] in which 0–15.5 is considered to be “not depressed”; 16–20.5 is “mild depression”; 21–30.5 is “moderate depression”; and scores 31 or higher indicating an individual to be at-risk for “severe depression”. Thus, respondents scoring less than 16 were given information regarding the varied components of the Healthy Start program; respondents scoring between 16 and 20.5 were encouraged to contact the Mental Health Counselor and given his business card; respondents scoring between 21 and 30.5 were asked if they would like to speak with the counselor at that time or if an appointment could be set-up within the next three working days; respondents scoring 31 or greater were also asked if they would like to immediately make an appointment or speak with the counselor at that time. Services available to the women included bilingual psychiatrists, psychologists and Master’s level social workers who staffed the SAMHD’s mental health clinic.

Measurement—Depressive Symptoms

The Center for Epidemiologic Studies-Depression scale was used to assess depressive symptoms [21]. The CES-D has been used in many community-wide epidemiologic surveys of depression, among various ethnic and age groups. The twenty questions assess the frequency with which depressive symptoms have occurred within the previous week using a four-point response scale: “Rarely or None of the Time” (Less than 1 day); “Some or a Little of the Time” (1–2 days); “Occasionally or a Moderate Amount of Time” (3–4 days); and Most or “All of the Time” (5–7 days). The questionnaire begins by asking: “During the past week”, followed by statements such as: “I had trouble keeping my mind on what I was doing”; “I felt depressed”; and, “I felt that everything I did was an effort”.

Total scores on the CES-D can range from 0 to 60 with higher CES-D scores indicating a higher risk of depression. Reliability tests conducted during field trial data testing for the CES-D have reported coefficient alphas of .84, .85, and .90 [21]. The CES-D has undergone reliability and validity testing among multiple ethnic groups, both in the U.S. and internationally [22]. In one study conducted by Roberts et al. [23], scores on the CES-D for Anglo and Mexican respondents were similar irrespective of language or ethnic status. Among studies with Mexican-American samples, high Cronbach’s alphas (.85–.88), were reported [24, 25].

The CES-D has also been used with pregnant and postpartum women. A study conducted among pregnant and postpartum Mexican-American women reported the alpha coefficient to be .87 (antenatal), and .88 (postpartum) [6].

A cut point of 16 has been employed in many studies to distinguish between high and low levels of symptoms [21]. However, there is overlap between depressive symptoms and certain manifestations of pregnancy and the early postpartum period, such as increased fatigue, sleep and appetite changes, and this may affect CES-D scores. To compensate for this overlap, investigators have used a higher cutoff score for the CES-D with pregnant and postpartum women [26, 27]. Several studies with Latinas have used a cutoff score of 24 [16, 28]. This study used two cutpoints: 21 to indicate the presence of moderate to high levels of depressive symptoms [20], and a score of 24 to indicate the presence of high depressive symptoms.

The Institutional Review Boards of Our Lady of the Lake University and the San Antonio Metropolitan Health District approved the original study conducted by the San Antonio Metropolitan Health District. The Committee for the Protection of Human Subjects of The University of Texas Health Science Center approved this secondary analysis as exempt.

Data Analysis

A prevalence rate of elevated depressive symptoms for the sample of Latinas (U.S.-born and those born in Mexico), was established, using a cutoff score of 21 to denote moderate to high levels of depressive symptoms and 24 to denote high depressive symptoms. Initial cross tabulations were conducted for the purposes of describing the overall sample and its characteristics by birthplace. The association of depressive symptoms and other study variables was assessed with Pearson’s chi-square test of independence, using an alpha level of .05. A nonparametric test for trends was used to test the association with ordinal variables, e.g., age categories. This is reported as a chi-square test with one degree of freedom [29].

Logistic regression analysis was conducted to assess the relative contribution of study variables in predicting depressive scores (CES-D ≥ 21) and (CES-D ≥ 24). Due to multicollinearity with birth country, language of interview was not included in this analysis. 91% of Mexican-born Latinas preferred Spanish for their interview while 95% of U.S.-born Latinas chose English; high collinearity is shown by this.

Results

Demographic Characteristics

Table 1 summarizes the demographic characteristics of the sample, reported by birth country. Mexican-born Latinas were significantly more likely to be older and were more likely to be married, to have conducted their interview in Spanish and to be pregnant.

Table 1 Sample demographics of pregnant and postpartum Latinas
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Elevated Depressive Symptoms (CES-D ≥ 21 and CES-D ≥ 24)

Table 2 reports the prevalence of depressive symptoms by cutoff scores and selected variables. Employing a cutoff score of 21 on the CES-D, 21% of the sample (95% C.I. 17%–25%), had moderate to high levels of depressive symptoms. Women who were U.S.-born were significantly more likely then Mexican-born women to meet the cutoff score (28.1% compared to 17.9%, respectively). Women who conducted their interview in English (26.2%) were significantly more likely to express depressive symptoms compared to women who conducted their interview in Spanish (18.0%). Single women were much more likely than married women to have moderate to high levels of depressive symptoms (31.5% vs. 13.2%, respectively). Women who were pregnant at the time of interview were also much more likely to have a CES-D score of 21 or greater; 24.0% compared to 12.7% of women who were postpartum.

Table 2 Elevated depressive symptoms among Latinas by study aim variables
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Using a higher cutoff score, 15% of the sample (95% C.I. 12%–18%) scored 24 or higher on the CES-D. The same pattern of relationship was found as with the moderate to high cutpoint of 21.

Predictors of Elevated Depressive Symptoms

In a logistic regression model, moderate to high levels of depressive symptoms (scores of 21 or above), were regressed on country of birth, age, marital status, pregnancy status and number of children for 437 cases (see Table 3). The Goodness-of-Fit Test of the model was 5.710, with eight degrees of freedom and a P-value of .680, indicating there was not a significant departure of the model from the data. Birth country, marital status and pregnancy status were significant predictors. Single women were three times more likely than married women and pregnant women were 2.5 times more likely to have a CES-D score of 21 or greater. Mexican-born women were significantly less likely to express moderate to high levels of depressive symptoms compared to U.S.-born women. Because of multicollinearity, it is not possible to precisely distinguish the effects of language and birth country. Age and number of prior children were not associated with moderate to high levels of depressive symptoms.

Table 3 Adjusted odds ratios and 95% confidence intervals for moderate to high levels of depressive symptoms (cutoff score of 21). Adjusted for birth country, age, marital status, pregnancy status, number of children (N = 437)
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Table 4 reports the results of multiple logistic regression analysis, for women meeting or exceeding the cutoff score of 24. In this logistic regression model, high depressive symptoms were regressed on the same variables as the previous model: country of birth, age, marital status, pregnancy status and number of children for 437 cases (see Table 4). The Goodness-of-Fit Test of this model was 8.094, with eight degrees of freedom and a P-value of .424, indicating there was not a significant departure of the model from the data. With this higher cutoff score, only marital status and pregnancy status were found to be significant predictors of high depressive symptoms. When controlling for the effects of other variables, single women were four times more likely to have a CES-D score of 24 or greater; pregnant women were also four times more likely than postpartum women to have high levels of depressive symptoms. Although birth country was not significantly related to predicting high depressive symptoms, the direction of effect was the same as found with the previous model. As was found in the previous model, age and number of prior children were not associated with high depressive symptoms.

Table 4 Adjusted odds ratios and 95% confidence intervals for high depressive symptoms (cutoff score of 24). Adjusted for birth country, age, marital status, pregnancy status, number of children (N = 437)
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Discussion

The level of high depressive symptoms among Latinas in the perinatal period has ranged from 12% [30] to 59% [16]. These studies have used diverse instruments and cutoff scores. Our study found 15% (95% C.I. 12%–18%) of pregnant and postpartum women to have high levels of depressive symptoms (CES-D ≥ 24) and 21% (95% C.I. 17%–25%) with moderate to high levels of depressive symptoms (CES-D ≥ 21), placing this study towards the lower end of the prevalence spectrum among Latinas.

The concept of acculturation as an explanatory variable in describing health inequalities is based on a conceptual model which theorizes that individuals, according to their cultural beliefs, choose or reject certain behaviors which in turn, affects their health [31]. Using birth country and language of interview as indicators of acculturation, Latinas who were more acculturated, i.e., U.S.-born and conducted their interview in English, were significantly more likely to express both moderate and high depressive symptoms. Comparing CES-D scores by birth country, Latinas who were U.S.-born reported higher CES-D scores than Latinas born in Mexico. The mean CES-D score among U.S.-born Latinas was 14.95 ± 11.1 SD, compared to 12.7 ± 10.2 SD, for Mexican-born Latinas.

In the bivariate analyses, English language and being U.S.-born were positively associated with depressive symptoms at both levels. In addition, being U.S.-born was associated with moderate to high levels of depressive symptoms when controlling for other variables. At the more stringent cutpoint of 24, birth country was not statistically significant, though the direction of effect was the same. Our results largely support the positive relationship of acculturation and depressive symptoms. Prior inconsistencies in the literature relating acculturation and depressive symptoms during the perinatal period may be due to diverse measures, variable populations and small sample sizes.

It is important that depressive symptoms were most strongly related to being pregnant and being unmarried. It may be that pregnancy and marital status assess aspects of the women’s lived experiences that are more proximal and intimate than language and country of birth, indicators of acculturation, and are hence more relevant to depression during the perinatal period. Future research will need a fuller array of cultural influences including family networks, views toward pregnancy and childbirth, and support patterns.

With respect to pregnant women being at higher risk for suffering from elevated depressive symptoms, among Latinas, higher levels of depressive symptoms have been found during pregnancy [32]. In a study conducted by Yonkers et al. [33], half of the study’s Latino and African-American women experienced the beginning of major depressive disorder during their pregnancy. These findings, along with others from previous studies, have suggested the importance of screening for depression/depressive symptoms during pregnancy [34].

The finding that women who are unmarried are more likely to be expressing elevated depressive symptoms is highly important. In 2005, 37% of all births and 48% of all births to Latina in the U.S. were to women who were single, the highest level ever recorded [35]. As births to Latinas increase in Texas (where 50% of all births are to Latinas) and in the U.S., these findings are especially relevant [36].

Future studies should also incorporate information regarding income and education since poverty has been demonstrated to be a strong predictor of depression among women in general. Although this study did not collect data about socioeconomic status, women attending public health clinics are likely to be of low income status. Future studies conducted among Latinas should include women from diverse socioeconomic groups to assess the effect of poverty on depressive symptoms in this population group.

Limitations of this study include the use of a convenience sample rather than a probability based sample and the inability to assess the rate of response. The sample may not be representative of women who visited the Family Planning and Prenatal Clinics at the San Antonio Metropolitan Health District. Because the data collected was from a public health clinic and limited to Latinas born in the U.S. or Mexico, the information cannot be generalized to represent all Latinas or Latinas of low socioeconomic status.

This study addresses a gap in studies of depression in a group of Latinas of Mexican-origin during the perinatal period. Relative to prior studies, its sample size is relatively large with adequate numbers of both foreign-born and U.S.-born women. A further strength is its use of a standardized instrument which has been the focus of extensive psychometric research. It also serves practice objectives by documenting the prevalence of depressive symptoms among a low-income, minority sample attending the San Antonio Metropolitan Health District public health clinics.